Patent foramen ovale

Patent Foramen Ovale

What is a patent foramen ovale (PFO)?

The foramen ovale (say "fuh-RAY-men oh-VAL-ee") is an opening in the heart's septum. This is the part that separates the upper right and left chambers (atria) of the heart. In a fetus, this opening has a flap of tissue that acts like a one-way door—it allows blood to flow to the left side of the heart without going to the lungs. It is kept open by the pressure of the blood that passes through it.

Normally, when a baby is born and takes a first breath, blood starts to flow through the lungs. The foramen ovale usually closes after birth. But sometimes it stays open and is called a patent (say "PAY-tunt") foramen ovale, or PFO.

A PFO usually doesn't cause problems as the person gets older. But sometimes it can lead to problems such as a stroke.

How is a patent foramen ovale (PFO) diagnosed?

Your doctor will ask you about your health history. You may also get some tests. These may include a special echocardiogram of your heart. This test uses bubbles and images to look for the hole in the septum of the heart.

©2011-2025 Healthwise, Incorporated

The content above contains general health information provided by Healthwise, Incorporated, and reviewed by its medical experts. This content should not replace the advice of your healthcare provider. Not all treatments or services described are offered as services by us. For recommended treatments, please consult your healthcare provider.

Walk-in services

Find a walk-in clinic

Same-day primary care services

Learn more

Onsite diagnostic tests

Find same-day care

Heart transplants

Learn more